Method of roughing slab to predetermined width and apparatus thereof

ABSTRACT

When roughing a continuously cast slab in a continuous hot rolling stand, the invention breaks down the width of the slab, having passed through a vertical scale breaker, by means of rolls having at least a pair of pressing calibers and thereafter the width of the slab is rolled by means of vertical rolls whereby the width of the slab is rolled more accurately than was possible in the prior art, and accordingly changes of molds of continuous casting machines are no longer required during the continuous casting operation and such an operation is possible over many charges.

United States Patent Kawawa et al.

[ Sept. 11, 1973 METHOD OF ROUGHING SLAB TO PREDETERMINED WIDTH AND APPARATUS THEREOF Nippon Kokan Kabushihi Kaisha, Tokyo, Japan Filed: Mar. 31, 1971 Appl. No.: 129,777

Assignee:

US. Cl. 72/234, 72/366 Int. Cl B211) 13/08 Field of Search 72/226, 225, 234,

References Cited UNITED STATES PATENTS Orr et al. 72/199 X 3,336,778 8/1967 Follrath 72/226 X 3,580,032 5/1971 Stone 72/199 3,557,595 [/1971 lllert 72/237 3,367,162 2/1968 Kazebee et al. 72/237 X 3,296,513 1/1967 Morton 72/10 3,323,342 6/1967 Baker 72/200 3,688,548 9/1972 Kawaguchi et al. 72/237 X 3,587,275 6/1971 Brennan 72/199 Primary Examiner-Milton S. Mehr [57] ABSTRACT When roughing a continuously cast slab in a continuous hot rolling stand,'the invention breaks down the width of the slab, having passed through a vertical scale breaker, bymeans of rolls having at least a pair of pressing calibers and thereafter the width of the slab is rolled by means of vertical rolls whereby the width of the slab is rolled more accurately than was possible in the prior art, and accordingly changes of molds of continuous casting machines are no longer required during the continuous casting operation and such an operation is possible over many charges.

12 Claims, 11 Drawing Figures 1 1 l6 1 H7 O 17 Patented Sept. 11, 1973 3,757,556 I 4 Sheets-Sheet 1 (PRIOR ART) F IG.2

IO D

INVENTORS TAKAHO KAWAWA MASAMOTO KAMATA TAKESHI HIRASAWA YOSHISUKE IKEGAMI BY w ,4-

ATTORNEY Patented Sept. 11, 1973 4 Sheets-Sheet 2 FIG.3

FIG.4

FIGS

PRIOR ART INVENTORS TAKAHO KAWAWA MASAMOTO KAMATA TAKESHI HIRASAWA YOSHI SUKE IKEGAMI BY M 6 ATTORNEY Patented Sept. 11, 1973 3,757,556

4 Sheets-Sheet 4 INVENTORS TA KA HO KAWAWA MASAMOTO KAMATA TAKESHI HIRASAWA YOSHISUKE IKEGAMI ATTORNEY METHOD OF ROUGHING SLAB TO PREDETERMINED WIDTH AND APPARATUS THEREOF BACKGROUND This invention relates to a method of roughing slabs to a predetermined width and an apparatus for carrying out same, and more specifically to such a technique suitable for roughing slabs of thin plate material which may be obtained from a continuously casting process.

In producing thin steel plate materials it is necessary to predetermine the width of the slab as closely as possible to that of the product. The slab may be rolled to the thickness of the final product in subsequent processes. The thickness may be rolled and altered easily, however, the width dimension is difficult to alter. The width of a thin plate material may vary substantially from 700 mm to 2,000 mm with the upper limit approximately three times the lower limit. In order to obtain a slab having a width approximating that of the product, prior art methods and apparatus employ means for controlling the ingot sizes, or means for controlling the hot strip mill comprising the rougher. However, these prior art methods and apparatus are unsatisfactory in that the controlling of those steps are in themselves limited. It has been thought that if the desired width could be obtained by controlling the hot strip mil, the operation could be performed satisfactorily. However, it was found that the width could only be controlled in the hot strip mill to about 40 to 60 mm at best. The first step using a vertical scale breaker would reduce the width a maximum of 40 mm. In subsequent stands, which roll the slab alternately in the longitudinal and latitudinal directions, the width is not substantially altered.

Even if the hot strip mill is furnished with four or five stands, it was found that the width would only be rolled to about 20 mmm at best by use of the subsequent rolls. This disadvantage is well known to workers in this field. Thus, most of the prior art methods of obtaining slabs of thin plates use widening rolling in the blooming roll. With this method, the slab is obtained whose width is about that of the product. However, this method requires a special blooming process for the once-cast ingot, and furthermore the operation is complicated and is not advantageous.

Using a continuous casting technique, a slab whose width is about 2,000 mm at the maximum is continuously obtained. If the merits of the continuous casting process are fully utilized it is possible to eliminate the casting-ingot process and the blooming process subsequent thereto, which method forces the treatments to be intermittent, and instead enable the roll slab to be obtained directly from the continuous casting. It is possible to directly rough slab by casting, followed by feeding it to a tandem strip mill, and for obtaining slab of thin plate. With such a technique, the size of the mold at the time of continuous casting must be varied in view of the technical circumstances, according to the predetermined width. However, when the size of the mold is changed, the width is also changed. Thus, to obtain different widths of thin plate materials, the mold size of each charge must be changed. After casting the steel in each charge, there is some delay while changing the casting mold. Thus, this method reduces the operating rate of the continuous casting process.

SUMMARY OF THE INVENTION The present invention is based on inventors discovery that if the width of continuous cast slab can be rolled to a certain range of widths by roughing stands placed in front of a tandem mill, the hot strip material, being within that range, can be applied with such a slab which is cast in the mold of a fixed size. According to this invention, it is not necessary to stop the casting for each melting as is now necessary using conventional methods. The melting of at least several times can be continuously performed with a mold of a fixed size, so that the advantageous merits of continuous casting may be enjoyed at its maximum and the operating rate of the continuous casting process may be elevated.

BRIEF DESCRIPTION OF DRAWING FIG. 1 shows an arranging line of rolls of the conventional continuous rough-rolling mill;

FIG. 2 depicts an arranging line of rolls of one of the continuous rough rolling mills of the invention;

FIG. 3 shows the front view of a calibered edging roll using the invention;

FIG. 4, shows a deformed condition of the material using a convention flat edging roll;

FIG. 5, shows the deformed condition of a material using the calibered edging roll of the invention;

FIGS. 6A, 6B and 6C show an arrangement of rolls of a continuous rolling mill using the scheme of FIG. 2;

FIG. 7, shows an arrangement of rolls used in a reversible rolling mill; and

FIGS. 8A and 8B show two arrangements of rolls employing the scheme of FIG. 7.

DETAILED DESCRIPTION OF INVENTION FIG. 1 depicts an arranging line of rolls of a conventional rough rolling mill in which the rolling reduction of the width of the roughed plate by action of a first step vertical scale breaker 1 is 40 mm at maximum, and reduction caused by the four stands 2,3,4 and 5 subsequent thereto is about 20 mm at maximum. The entire rolling reduction is about 60 mm. For this reason the vertical rolls for adjusting the width arranged in front of the second stand of the horizontal rolls are flat edging rolls. In case of strong rolling of the width, only selvages of the slab are rolled. The deformation is not uniformly spread to the width, and the slab is subject to buckling.

The present invention offers a rough rolling method for rolling the width of the slab, in which the vertical rolls having at least a pair of calibers, are arranged in front of horizontal rolls. The continuous roughing mill generally operates the hot-rolling at the finishing temperature of more than A transformation, e.g., when the proeutectoid ferrite or cementite is substantially absorbed into austenite, preferably at about l,100C to 1,300C. The vertical rolls may also be in front or close to the horizontal rolls of a reversible type roughing mill. Since arrangement of such a calibered vertical roll is not limited to rolling only on selvages, as was true in prior art methods, and hence does not cause buckling, as was true in prior art methods, advantageously using this invention, it is possible to roll the width in a range of widths larger than 'in prior art roughing mills, and thus increase the operating rate of the finishing. It also enables full enjoyment of the continuous casting, and also reduces crop losses (i.e., losses of material due to long extrusion from both ends of the slab by rolling to predetermined width) in comparison to methods employing application to each slab.

FIG. 2, depicts an embodiment of the invention in which an arrangement of rolls comprise vertical scale breaker 10, and third stands 13,14, and 15 each comprising a pair of flat edging rolls l6 and horizontal rolls 17.

The first stand 11 is arranged with the horizontal rolls 17 and two pairs of calibered rolls 18, which are for rolling the width according to the invention, and is used instead of the prior art flat edging rolls.

The second stand 12 is, in the rolling order, comprised of calibered vertical rolls 18, flat edging rolls 16 and horizontal rolls 17.

The calibered vertical rolls 18 are shown in greater detail in FIG. 3. The rolls 18 are, as depicted, formed with calibers at their periphery. These rolls 18, advantageously, are not limited to rolling only selvages, as is the case with prior art flat rolls, but instead enable uniform deformation of the slab as to width because the slabs are inserted into the calibers. Moreover, advantageously, buckling is not produced, as was inherent with prior art methods. Accordingly, heavy rolling is possible with this invention.

The most preferable ranges of the calibered vertical rolls shown in FIG. 3, although not limited thereto, are:

Bottom diameter D of roll caliber-600 to 1,200

Depth B of caliber part 100 to 600 mm.

Bottom width H of caliber 50 to 100 percent of slab thickness.

External edge R of caliber 50 to 100 mm.

Bottom r of caliber to 20 mm.

Oblique angle a of caliber side 3 to 12.

The rolling reduction of the width in the first step with the inventive calibered rolls, will be more or less different depending upon the width of the slab. However, generally, it is preferable to attain the object of 120 mm (substantially 80 to 90 mm) in the case of the width being more than 1,400 mm, and to aim for 150 mm (substantially 120 to 130 mm) in the case of widths of not more than 1,400 mm. The thickness of the slab affected with compression to the width may be voluntarily chosen, but it is preferable to have the thickness reach the objective of more than 180 mm, preferably around 200 to 350 mm.

In this connection, a horizontal pinch roll 19 may be placed prior to the first stand 11, in which case the deformation amount is substantial in the case of such calibered rolls.

In the entire design scheme, about 2 or 3 molds for continuous casting may be used to produce the slabs, the widths of which vary as much as from 700 to 2,000 mm. Using molds of for example I,000,1,500 and 2,000 mm in width, the thin plate of from 700 mm to 2,000mm in width can be produced. It is desireable to both continuous casting operation and rolling operation that any of the slabs can be produced, with two or three molds, nd that the and of the calibered rolls shown in FIG. 2, be designed so as to provide a reduction of widths of from 400 mm toSOO mm at maximum. In other words, if the rolling reduction by one calibered roll is about 150 mm, three arrangement can provide a reduction of about 450 mm. The rolling reduction of about 50 mm by the scale breaker may be added thereto, thereby to reduce the width about 500 mm to 600 mm at a maximum. The three stands of the third and subsequent stands are useful to accurately control the thickness and width of the slab rolled to the predetermined width, and are arranged successively to the subsequent tandem rolling.

FIGS. 6a, 6b and 6c show three embodiments of arranging rolls of a continuous rough rolling mill. Such an arrangement takes into consideration the special circumstances of the factory employing same, and using the scheme of FIG. 2. Depicted (in FIG. 6a) are two pairs of calibered rolls arranged at the first stand 11 only. In FIG. 6b are a pair of calibered rolls arranged respectively at the first and second stands 11 and 12. In FIG. 6c are three pairs of calibered rolls arranged at the first stand 11, and a pair thereof at the second stand 12. The first, second and third stands are the same in each of FIGS. 60, 6b and 6c and are as shown in FIG. 2.

FIG. 7 or FIGS. and 8b show the realized embodiments of a reversible rough-rolling mill, comprising a first stand 20 and a second stand 21. In this embodiment, the slab may be repeatedly reciprocated between the first and second stands. The first stand 20 comprises horizontal rolls 22, calibered vertical rolls 23, and the second stand 21 comprises flat edging rolls 24, and horizontal rolls 25. The calibered vertical rolls 23 are similar to that shown in FIG. 2. The horizontal rolls 22 of the first stand 20 serve the same purpose as the pinch rolls 19 in FIG. 2. After performing the necessary rolling by means of the calibered rolls 23, the thickness and width are adjusted by flat rolls 24 (See FIG. '7), and the horizontal rolls 25 (See FIGS. 8a, 8b) of the second stand 21, followed by feeding the slab to the subsequent tandem mill.

According to the rough-rolling mill of the invention, to alter the width of the slab, the rough rolling mill is furnished with at least one pair of calibered verticai rolls to roll the slab to a predetermined width. The invention avoids such possibilities as only rolling selvages, or producing non-uniform deformity, or buckling, as occur in prior art apparatus. This invention, advantageously, produces rolling to a large range of widths, enhances the advantages of continuous casting by enabling casting with a fixed mold, and increases the rate of operation of the mill.

The following examples are set forth showing the actual results of runs produced by the invention.

EXAMPLE 1 Rimmed steel, the contents of which were C,0.05 to 0.12%; Mn,0.3 to 0.6%; Si,0.05 to 0.15%; P,less than 0.03%; S,0.03% and Al,0.005 to 0.02%, was passed through continuous casting to provide a slab of width 1,910 mm and thickness about 1,230C and fed into FIG. 2 line at a temperature of 225 mm. The slab was extracted at/around 1,200C at the entrance of the rough-rolling mill. The variances of the width at the respective roughing stands are shown in Table 1, and the width became finally 1,470 mm. The reduction of width was 440 mm and the temperature was 1,080C at the exit of the rough rolling mill.

EXAMPLE 2 Al killed steel, the contents of which were C,0.04 to 0.06%; Mn,0.2 to 0.6%; Si, trace; P,less than 0.025percent; S,less than 0.02% and Al,0.25 to 0.65%, was changed into a slab of width 1,600 mm, thickness 200 mm, and length 8,000mm. The slab was extracted at 1,250C from the furnace and fed at 1,200C to the rough rolling mill to be roughed. The temperature thereof was l,O70C at the exit of the rough rolling mill. The variances of the width and thickness at the respective stands of the reversible rough rolling mill are shown in Table 2.

rough widths said slab is rolling using flat edging rolls and horizontal rolls.

4. Method of claim 1, wherein scales are first re moved from said slab by vertical scale breakers, and wherein horizontal rolls support said slab during said rough width rolling.

5. Method of claim 1, wherein said slab is reversibly TABLE I Rolling Draft Thlck- Compress- Thickreduction percentage ness ibilit ness of thickof thick- Station (mm) (mm.) (mm.) ness (mm.) ness Slab Vertical scale breaker 1st Stand- 1st calibered roll 2nd calibered r011.

Horizontal roll 2nd Stand:

Calibered roll TABLE 2 Rolling Draft Compress- Thickreduction percent- Wldth ibility ness of width age of Pass No. Station (mm.) (mm.) (mm.) (mm.) width Slab 1, 600 200 1 {Horizontal roll 22.... 1,600 0 195 Calibored roll 23.... 1, 140 210 {calibered roll 23.--.. 1, 300 160 225 Horizontal roll 22.... 1,310 215 3 {Horizontal roll 22.... 1, 320 +10 200 Cnllbered roll 23.... 1, 200 120 210 4 {Flat roll 24 180 Horizontal roll 25.... 1, 210 160 5 {Horizontal roll 25.... 1 230 +20 110 Flatroll 24... 1,215 16 6 {Flat roll 24... 1, 200 -15 Horizontal roll. 1, 210 +10 70 -40 36. 4 7 {Horizontal roll 2 1, 220 +10 42 28 40. 0 Flatroll24. 1,215 5 8 {Flat roll 24. 1, 215 0 Horizontal r 1, 220 +5 26 16 38. 1

properly considered within the spirit and scope of this invention.

What is claimed is:

1. Method of width rolling to obtain improved rough dimensioning of the width of a continuous or noncontinuous cast slab with one or more rolling stations comprising the steps of feeding said slab to said one or more rolling stations, rolling at one of said rolling stations each width end of said slab by application of a force to each of said width ends in a direction substantially parallel to the width direction and in a plane perpendicular to said width direction and extending substantially along the thickness of said slab and concurrently therewith application of a set of forces to each of said width ends in directions at opposing oblique angles to said plane, and rolling said slab to thickness at one or more of the other rolling stations.

2. Method of claim 1, wherein said forces are applied by one or more pairs of vertically oriented calibered rolls, with said oblique angles formed by the calibered lips ranging from 3 to l2 to said plane, and wherein said slab is continuously cast.

3. Method of claim 1, wherein after rolling to obtain reciprocat e d toeffect repeated application of forces to said width edges.

6. Method of claim 1, wherein said slab is compressed repeatedly to be reduced in width by 500 mm to 600 mm.

7. Apparatus for improved rough width rolling of a continuous or non-continuous cast slab, comprising means for compressing the width end portions of said slab with concurrent pressures applied to both said width ends in a plane with the thickness dimension about the thickness of said slab and in planes disposed at opposing oblique angles to said one plane at said ends, means for feeding said slab to said means for compressing, and means for thickness rolling said slab.

8. Apparatus of claim 7, wherein said means for compressing comprises one or more pairs of vertical caliber rolls, and said means for feeding comprises a horizontal roll, and further comprising vertical scale breakers positioned before said calibered rolls.

9. Apparatus of claim 7, wherein said means for compressing comprises a plurality of vertical calibered rolls, and further comprising vertical edge rolls and horizontal rolls with one or more pairs of said claibered being disposed selectively adjacent to one or more of said vertical edge rolls and said horizontal rolls.

10. Apparatus of claim 9, wherein said oblique angles are between 3 and 12.

11. Apparatus of claim 7, further comprising means for operating said apparatus in a reciprocal reversible manner.

12. Method of substantially accurately rough dimensubstantially flat horizontal position, moving said supported slab in a horizontal direction, and while said slab is moving concurrently forming a substantially fiat end on said width edge of said slab and adjacent thereto on sioning at least one width edge of a continuously cast both sides of said width edge an angulated bulge.

slab, comprising the steps of supporting said slab in a 

1. Method of width rolling to obtain improved rough dimensioning of the width of a continuous or non-continuous cast slab with one or more rolling stations comprising the steps of feeding said slab to said one or more rolling stations, rolling at one of said rolling stations each width end of said slab by application of a force to each of said width ends in a direction substantially parallel to the width direction and in a plane perpendicular to said width direction and extending substantially along the thickness of said slab and concurrently therewith application of a set of forces to each of said width ends in directions at opposing oblique angles to said plane, and rolling said slab to thickness at one or more of the other rolling stations.
 2. Method of claim 1, wherein said forces are applied by one or more pairs of vertically oriented calibered rolls, with said oblique angles formed by the calibered lips ranging from 3* to 12* to said plane, and wherein said slab is continuously cast.
 3. Method of claim 1, wherein after rolling to obtain rough widths said slab is rolling using flat edging rolls and horizontal rolls.
 4. Method of claim 1, wherein scales are first removed from said slab by vertical scale breakers, and wherein horizontal rolls support said slab during said rough width rolling.
 5. Method of claim 1, wherein said slab is reversibly reciprocated to effect repeated application of forces to said width edges.
 6. Method of claim 1, wherein said slab is compressed repeatedly to be reduced in width by 500 mm to 600 mm.
 7. Apparatus for improved rough width rolling of a continuous or non-continuous cast slab, comprising means for compressing the width end portions of said slab with concurrent pressures applied to both said width ends in a plane with the thickness dimension about the thickness of said slab and in planes disposed at opposing oblique angles to said one plane at said ends, means for feeding said slab to said means for compressing, and means for thickness rolling said slab.
 8. Apparatus of claim 7, wherein said means for compressing comprises one or more pairs of vertical caliber rolls, and said means for feeding comprises a horizontal roll, and further comprising vertical scale breakers positioned before said calibered rolls.
 9. Apparatus of claim 7, wherein said means for compressing comprises a plurality of vertical calibered rolls, and further comprising vertical edge rolls and horizontal rolls with one or more pairs of said claibered being disposed selectively adjacent to one or more of said vertical edge rolls and said horizontal rolls.
 10. Apparatus of claim 9, wherein said oblique angles are between 3* and 12*.
 11. Apparatus of claim 7, further comprising means for operating said apparatus in a reciprocal reversible manner.
 12. Method of substantially accurately rough dimensioning at least one width edge of a continuously cast slab, comprising the steps of supporting said slab in a substantially flat horizontal position, moving said supported slab in a horizontal direction, and while said slab is moving concurrently forming a substantially flat end on said width edge of said slab and adjacent thereto on both sides of said width edge an angulated bulge. 